Printing telegraph apparatus



March 19, 1940. KRUM ET AL 2,193,970

PRINTING TELEGRAPH APPARATUS Original. Filed May 4, 1936 "2 Sheets-Sheet 1 a? FIG. I I84 :83

49 94 a4 59 I as 52 6| I06. o 6 89 57 5| 6 ,1 Y

64 5 4 9 6 g; H3 l 32 79 I37|32 n2 I33 117 I o2 I25 l2 29 e 27 I28 32 27I8 ya [I I 29 33 Zinnentor O HOWARD L. KRUM CARL w. SWAN V (IttornegMarch 19, 1940. M r L 2,193,970

PRINTING TELEGRAPH APPARATUS I Original Filed May ,4, 1956 sheets-sneet2 FIG. 6

Snventor HOWARD L. KRUM CARL W. SWAN I8 I84- Y J I ttorneg Patented Mar.19, ,1940

UNITED STATES PATENT OFFICE PRINTING TELEGRAPH APPARATUS lioward L.Krum, Miami Beach, Fla., and Carl W. Swan, Chicago, Ill., assignors toTeletype Corporation, Delaware Chicago, Ill., a corporation of 2 Claims.

The present invention relates to printing telegraph apparatus andparticularly to apparatus for recording messages.

This application is a division of application Serial No. 77,794, filedMay 4, 1936, and relates more specifically to means for driving the typewheel, in which the type wheel is sleeved upon its shaft and rotation isimparted to the type wheel at a point upon its periphery by means of anarm which is secured to the shaft.

The primary object of the invention is to prov.de in a type wheel pageprinter simple and eflicient means for effecting the printing operation.

Briefly, the printing telegraph apparatus for which the type wheel inaccordance with the invention has been particularly developed, comprises a typing unit removably mounted on a keyboard mechanism whichcarries a permutation code transmitting mechanism. The typing unitcomprises a single magnet selector which is articulated to a permutationcode disc selector, the discs of which are adapted to be setpermutatively in accordance with signals received by the single magnetselector. When permutatively positioned the code discs select one of aplurality of stop pins and permit it to be positioned in the path of anarm carried by a rotatable shaft, which is motor driven through afriction clutch and on which a type wheel is mounted. The type wheelthus may be stopped in various angular positions in accordance with theselection of stop pins. A rotatable page width paper platen is mountedin alignment with thetype wheel in a reciprocable carriage mounted on afoundation portion of the typing unit and arranged to be moved step bystep by power mechanism to effect spacing and to be returned to linebeginning position by the energy stored in a spring.

The single magnet selector mechanism includes a cam barrel assemblywhich is frictionally connected to a power driven shaft to be rotatedthereby and which controls the operation of the selector mechanism. Thelast mentioned power driven shaft also includes a set of operating camsmounted on a sleeve or bushing in fixed angular relation with respect toeach other and adapted to be driven by the shaft through a positiveclutch mechanism in which driving connection is established under thecontrol of the selector cam barrel and which is disengaged automaticallyat the conclusion of a single revolution of the Operating cams. One ofthe 'cams is effective to operate a striker member which delivers a blowto a lever to which is connected a print hammer disposed interiorly ofthe type wheel at the inner end of operating shanks of charactercarrying elements mounted in the type wheel. The blow which is deliveredby the striker member is communicated through the print hammer to theshank of a character element which is thus caused to be reciprocatedtoward the printing platen. Another cam included in the operating camassembly operates carriage spacing mechanism and also performs certainnecessary stunts or functions. ball through the medium of which aselection established in the single magnet selector as a result of thereception of a code combination is transferred to the discs of the codedisc selector through the articulation between the two selector clampedby screws to the annular member and closes the tops of the slotstherein. A floating ring prevents accidental escapement of any of thetype pallets from the slotted member.

For a detailed description of the structure and operation of the variouselements, units, and

' combinations included in the typing unit, reference should be had tocopending application of Albert H. Reiber, Serial No. 77,796, filed May4, 1936, in which the entire printing telegraph mechanism is disclosedin greater detail.

For a complete understanding of the present invention, reference may behad to the following description, in which only as much of the detailsof the typing unit as is necessary to afford a complete understanding ofthe invention has been included, taken in connection with theaccompanying drawings in which:

Fig. 1 is a perspective view of the printing telegraph apparatusdescribed in detail in the aforementioned copending application andincluding the type wheel which constitutes the present invention;

Fig. 2 is an exploded perspective view of the type wheel assembly;

Fig. 3 is a plan view, partly in section, of the type wheel assembly andrelated apparatus;

A third cam operates a transfer,

Fig. 4 is a vertical sectional view through the type wheel and relatedapparatus; and

Figs. 5, 6 and 7 are perspective views of type pallets. 1

Referring now to the drawings, in which corresponding reference numeralsindicate identical parts in several views, and particularly to Fig. 1,the reference numeral Ii designates generally a keyboard transmittermechanism. For a detailed description of a keyboard transmittermechanism which may be employed as a part of the printing telegraphapparatus to be described herein, reference may be had to United StatesPatent No. 1,595,472, granted .iiugust 10, 1926, to Howard L. Krum. Ingeneral, the keyboard transmitter mechanism H comprises a base castingi2 which pivotally supports at I! a plurality of key levers [4. The keylevers I4 control the positioning of code bars (not shown) whichcorrespond in number to the selecting impulses in the particulartransmitting code which may be employed and to each of which isarticulated a lever i9 extending upwardly from within the base castingl2.

A transmitting cam shaft i1 is rotatably mounted in bearing supports I9carried by the base casting I 2 and has fixed thereto a gear i9 which isdriven by a gear train comprising the gears 2| and 22 from a gear 23,the drive for which will be described later. The gear i9 has connectedthereto the driving portion of a tooth clutch 24, the driven portion ofwhich is connected to a cam sleeve 29. The driven portion of clutch 24is urged by spring thrust into engagement with the driving portion andis normally restrained from engagement therewith by a clutch throw-outlever 21 which is withdrawn from restraining engagement with the drivenportion of the clutch, by linkage not completely shown, when any one ofthe key levers I4 is actuated. 4

The cam sleeve 29 carries a plurality of transmitting cams 29 each ofwhich includes a notch 29. A transmitting bell crank lever ii ispivotally mounted in alignment with each of the cams 29 and each leverII has an arm (not shown) which carries a cam follower (also not shown)for following the particular cam 28 with which the lever is aligned. Thecam follower of each of the transmitting bell crank levers 3| tends todrop into the notch 29 in its associated cam when the notch is presentedto the follower but the pivoted levers ii are effective when they occupycertain positions to block the cam follower arms of the bell cranklevers 9| to prevent the cam followers from dropping into the notches29. It will thus be apparent that as the cams 29 rotate, certain of thebell crank levers 9| will be permitted to rock and others will berestrained by the levers l9 and the rocking or non-rocking condition ofthe levers 9! will depend upon the permutative setting of the levers IS.The notches 29 in the several cams 28 are displaced from each other soas to be aligned helically, with the result that the bell crank levers3| are released successively as the cams execute one revolution.

Transmitting contacts 92 are associated with each of the transmittingbell crank levers 3!, so that electrical contact is established when abell crank lever is rocked and an open circuit condition is maintainedwhen a bell crank lever II is restrained from being rocked. Theelectrical contacts 22 may be connected to a telegraph line and to theselector magnet of the typing unit to be described hereinafter, so thatmarking and spacing impulses may be set up by the several contacts 22 inaccordance with the positioning of the levers [9. A knife edge 93 iscarried by a pivoted ball 94 which has an arm 99 provided at its outerend with a follower roller 21 which follows a cam 29 carried by the camsleeve 29. The knife edge 22 drops into blocking engagement with lugs 39carried by the levers II when the cam barrel 29 rotates, to preventaccidental shifting of the levers I. while a code combination is beingtransmitted.

The typing unit or receiving portion is designated generally by thereference numeral 4i and is removably mounted on the base casting l2 bysuitable bolts, not shown. The foundation of the tpying unit 4i consistsof two castings upon which all of the receiving mechanism is mounted.One of the castings is designated 42 and extends from front to rear ofthe base casting l2 substantially parallel with the transmitting camshaft ll. The other casting designated 42, is

also mounted on the base casting i2 and extends across the base castingl2 near the rear end thereof, substantially at right angles to thecasting 42..

The casting 42 has secured thereto, bearing blocks 49 in which isrotatably mounted a vertical shaft which carries previously mentionedgear 22 and other mechanisms to be identified later. The gear 23 isfixed to the vertical shaft and is arranged to be continuously drivenfrom the rotor shaft of an operating motor not shown.

It will be noted that no reference character has been applied to theshaft upon which the gear 23 is mounted, the reason for this being thatin Fig. 1 the shaft is concealed by the various elements mounted uponit. In addition to the gear 23 by which it is driven, the unseen shafthas fixed thereto the driving portion 41 of a tooth clutch 49 and thespaced discs 49.

The discs 49 are adapted to drive a selector cam barrel Ii which isprovided at its opposite ends with discs 52. Friction discs 59 aredisposed between the discs 49 and 52, and the dam barrel 5i, discs 52,and friction discs 53 are confined between discs 49 under pressure sothat the cam barrel 5i when not under restraint is rotated by the discs49 fixed to the unseen shaft.

The cam barrel 9| constitutes an element of a single magnet selectorindicated generally by the reference numeral 59. The selector mechanism56 may be constructed in accordance with the teachings of United StatesPatent No. 1,937,- 376 granted November 28, 1933, to Walter J. Zenner.The selector mechanism 59 comprises a plate 51 mounted on the casting 42and having an aperture 58 through which the selector cam barrel 5iextends. The plate 51 has mounted thereon a selector magnet 59 to whichincoming signal impulses are applied and which, with the cooperation ofthe cam barrel 5| having helically arranged cam projections 6|, effectsthe setting of a selector lever 92 in the manner described in theabove-identified Walter J. Zenner patent. The selector lever 92 controlsthe operation of a sword-and-T lever selector assembly 69, alsocompletely described in said Walter J. Zenner patent, to effect thepermutative setting of lever arms 94 in accordance with impulses appliedto the selector magnet 59.

The lever arms 64 are provided at their outer ends with prongs 96between which are confined disc-like portions 91 of transfer bell cranklevers 68. The bell crank levers 59 are pivotally mounted maintains themin their proper positions.

at 88 and are provided at the outer ends of their arms II with disc-likeportions I2 disposed in notches formed in permutation code discs of apermutation code disc selector indicated generally by the referencenumeral I8.

The code disc selector may be of the type disclosed in United StatesPatent No. 1,821,110 granted September 1, 1931, to Sterling Morton etal., to which reference may be had for a detailed description of suchselectors. The selector comprises upper and lower spaced discs I8 and I1respectively, which have a plurality of open slots I8 radially arranged.The slots in the disc 11 are concealed, in Fig. 1, by selectable stoppins I8 extending from the lower disc 11 to the upper disc 18. The stoppins arejormed with loops 8| at their lower ends disposed in the slotsin the disc 11, and a garter spring 82 surrounds the pins 18 just abovetheir loop portions 8I and The pins I8 are of suflicient length toextend above the upper" disc 18. a

Below the upper disc I8 are rotatably mounted a plurality of code discsI5 (Fig. 4) individually aligned with the transfer levers 88 andprovided, as previously stated, with notches which receive the disc-likeportions 12 of transfer bell crank lever arms II. The code discs areprovided with permutation code notches in the peripheries thereof, sothat for eachpermutative setting of the code discs one completealignment of notches shall be effected. Whenan alignment of code notchesis thus effected, such alignment is presented opposite one of theselectable stop pins 18, which pivots about its point of engagement withthe disc 11, thus moving its upper end inwardly within one of thenotches 18 and into the path of a stop arm 88 fixed to a shaft 84rotatably mounted co'axially of the code disc selector mechanism I8. Theshaft 84 is kept under constant torque from the previously mentioneddriving motor (not shown) through a friction clutch and suitable gearing(also not shown). When one of the stop pins 18 enters the path of thestop arm 88, the latter rotates into engagement with the selected pin 19and is thereby stopped to present a selected portion of a type wheel 88,the structural details of which will be described later, carried byshaft 84 near the top thereof and driven therefrom, to a rotatableprinting platen 81 carried by a carriage 88. The carriage 88 isreciprocably mounted at the top of frame casting 48 and is urged to itsright-hand position by a carriage return spring contained within a drum89 which is engaged by one end of a belt 9|, the

other end- 0f which is connected to carriage 88. Suitable mechanisms forspacing the carriage and for'performing line feed and carriage returnoperations are provided and although not shown herein, are completelyshown and described in the above-mentioned copending application.

Above the code disc selector I8 and adjacent to the type wheel 88 isdisposed a feed mechanism for an inked printing ribbon, such as theinked ribbons employed in typewriters. The feed mechanism includes aplate 92, removably supported above the code disc selector mechanism,which rotatably supports pins 93. The pins have secured thereto, belowthe plate 92, feed ratchets 84, and above the plate 92 means (not shown)for engaging and driving the ribbon spools 88 mounted on the pins 98.The plate 92 has pivotally mounted thereon a lever 81 which has at itsleft-hand end a pivot pin 98 on which is pivotally mounted a ratchetfeed pawl 89 which is adapted to engage either of the ratchets 84, depending upon the direction in which the ribbon is to be fed, and rotatethe ratchet, as the lever 91 is rocked clockwise, to wind the ribbon onone spool, drawing it from the other spool. The right-hand end ofoperating lever 81 enters a slot I8I in a link I82 which is pivotallymounted at I88 on a power actuated lever I88 pivotally mounted at I81 toa bracket I88 secured to the frame casting 42.

Referring again to the tooth clutch 48, which is carried by the selectedcam barrel shaft, the

driven portion III is spring urged by spring II2 toward the drivingportion 41 and is restrained from engagement therewith by a clutchthrowout lever III pivotally mounted on a shaft II4. Connected to theclutch throwout lever H8 is a lever arm II8 disposed adjacent to the cambarrel 8| to be actuated by a cam projection thereon to effectwithdrawal of the throwout lever from restraining engagement with thedriven portion III of the clutch 48.

The driven portion III of the tooth clutch 48 is connected to drive asleeve III which has fixed thereto cams H8 and H8. Cam H8 is engaged byacam follower roller I2I carried by a lever I22 pivotally mounted onshaft I28. Lever I24 also pivotally mounted on shaft I28 is connected atI25 to cam follower lever I22, and engages the ribbon feed mechanismoperating lever I88 to impart counterclockwise rotation thereto whenlevers I22 and I24 are rotated counterclockwise by the action of cam II8on cam follower I2I Lever I24 carries pivot pin I28 to which arearticulated function performing bars I21 and carriage spacing pawl I28.

Above the cam H8 is box cam II8 which is provided with cam groove I29.Pivotally mounted on shaft I28 is a lever I8I which has a cam follower(not shown) disposed in the groove I29 in cam III) to be actuated by anoffset (not' shown) therein. Lever I8I is arranged to be rotatedcounterclockwise by cam H9, and has articulated thereto a reciprocablebar I82 which is provided with an abutment I88. A striker member I84pivotally mounted at I88 has an arm I81 disposed in the path of abutmentI88.

In Fig. 2 is shown an exploded view of the type wheel assembly 86. Thefoundation of the assembly is an annulus I having a groove I42 ofconstant depth and rectangular cross section in the periphery thereof,whereby upper and lower integral flanges I48 and I44 are provided. Itwill be apparent that the foundation might be constructed by securing,by any desired means, flat rings to the top'and bottom of an annulushaving a circumference equal to that at the base of groove I42, wherebythe flat rings would constitute flanges defining a groove. However, in'the embodiment shown in Figs. 2 and 4, the flanges are produced byforming the peripheral groove .in an annulus having an outside diameterequal to that of the flanges I48 and I 44. Radial slots I46 are cutthrough the upper flange I43, through the annular wall at the base ofthe groove I42,.and partially through the lower flange I44. The slotsI48 equal in number the possible permutation 1 code combinations in thecode upon which the, transmitting and receiving mechanism shownin Fig. lis intended to operate, and they are uni- In the small angular I43 isprovided with a cylindrical aperture I48 extending therethrough. Theflange I44 is provided in the upper face thereof with a cylindricalrecess I49 coaxial with the aperture I48. The slotted flange I43 isprovided with tapped holes I5I.

The slots I46 are intended to receive and slidably support and guidetype pallets I62, I63 and 203 shown in Figs. 2 to 7. As shown in Fig. 7,the type pallet I52 comprises a type carrying face I53 from the rear ofwhich extends a thin flat shank I54. The shank I54 enters one of theslots I46 and is guided in the vertical portion at the base of thegroove 42 as well as in the horizontal portion in the flange I44. Eachof the type pallets I52 which is adapted to seat at the bottom of a slotI46 is provided at the top of the shank thereof with a notch I58, and acoiled wire tension spring I51 seats in the recesses I56 and extendsaroundall the shanks I54 of the type pallets I52 and has hooks I58 atthe ends thereof engaging a cylindrical retaining pin I59, which isinserted in the grooved annulus I4I through the cylindrical aperture I48in flange I43 thereof, and which seats in the cylindrical recess I49 inflange I44 as shown in Fig, 4. The relationship between the depth of thegroove I42 and the distance of the inner end of type pallet shank notchI56 from the inner surface of the type carrying face I53 is such thatthe notch I56 is entirely within the groove I42 even when the innersurface of the face I53 abuts the flange I44. It will be apparent fromthis that the spring I51 is seated in the notches I56 within the grooveI42 and urges the type pallets-inwardly radially of the grooved annulusI4I so that the inner surfaces of type carrying faces I53 are urged intoabutment with the flange I44. It may be observed, by reference to Fig.3, that the type pallet shanks I54 are of sufficient length to extendinteriorly of the annulus I4I.

Directly above the spring I51 there is disposed a split ring I6I whichrests on the spring I51 and is of sufficient thickness to extend abovethe upper edge of the shank I54 a distance equal to the extent to whichthe ring enters the notch I56 therein. The periphery of the ring I6I isdisposed adjacent to the shoulder I62 in the shank of each of the typepallets I 52. The ring I6I extends outside of the pin I59 and restsloosely or floatingy upon the spring I51 and within the notches I56 inthe type pallet shanks I54.

Above each of the type pallets I52 there is disposed in the slots I46 atype pallet I63 similar to the type pallets I52 except that the typefaces I64 carry different characters than do the type faces I53, and thenotches I66 in the shanks I61 open downwardly instead of upwardly. Aspring I68 similar to the spring I51 and similarly engaging the pin I59is seated in the notches I66 in the type pallet shanks I61 and urges theinner surfaces of the type carrying faces I64 into engagement with theflange I43. The spring I68 presses downwardly upon the split ring I6Iand retains it centered within the groove I42 of annulus MI. The shanksof type pallets I63 rest upon the shanks of pallets I52 and since, aspreviously stated, the ring I6I is of suificient thickness to extendabove the upper edge of the type pallet shank I54, it manifestly extendsinto the notch I66 in shank I61 of type pallet I63.

A cover I1I for the grooved annulus I has an aperture in the centerthereof which receives the upper end of a hub member I12 which is fixedto the cover I1I in any convenient manner such as by upsetting as shownat I13 in Fig. 4. The cover III is provided on the lower surface thereofwith radially extending ribs I14, equaling in width the slots I46 inannulus I4I and spaced in accordance with the spacing of such slots. Atone point in its periphery the cover IN is provided with a recess orkeyway I16 corresponding to the recesses or keyways I41 in the flangesI43 and I44. The cover IN is adapted to seat on the upper face of flangeI43 with the ribs I14 entering the slots I46 and with the recess orkeyway I16 in alignment with the keyways I41. Clamping screws I11 enterapertures I18 in the cover HI and engage the threaded apertures I5I inflange I43 of annulus I to clamp the cover I1I securely to the flangeI43.

In this way a type wheel assembly is provided in which, as shown inFigs. 3 and 4, individual type pallets arranged in rows about theperiphery of the type wheel are retained in slots by springs I51 andI68, by split ring I6I and by cover I1I. Sufficient clearance isprovided between the ribs I 14 and the type pallets I63 to providefreedom of the pallets I52 and I83 for sliding movement radially of thetype wheel and within the slots of the annulus I4I thereof, within thelimits afforded by the annular retaining ring I6I. The springs I51 andI68 urge the type pallets to their innermost positions and the floatingring I6I prevents accidental displacement of the type pallets from thetype wheel structure in the event that one of the tension springs shouldbecome broken and no longer maintain the type pallets under tension.

As shown in Fig. 4, the type wheel shaft 84 is provided at its upper endwith a reduced portion I8I whereby there is provided a shoulder I62, Thehub I12 is adapted to be mounted upon the reduced portion I8I of thetype wheel shaft I84 with sufllcient freedom to be slidable with respectthereto and to seat, in its lowermost position, against the shoulderI62. An arm I83 is keyed to the type wheel shaft 84 at the upper endthereof and the arm I83 supports an arm I84 which is provided with slotsI86 through which pass clamping screws I61 which threadedly engage thearm I83 and thus adjustably clamp arm I84 to arm I83. Arm I84 isprovided at its outer end with depending arm I88 which enters therecesses or keyways I16 and I41 in the cover Ill and annulus I4Irespectively. The arms I83, I84, and I88 serve as driving connectionbetween the type wheel shaft 84 and the type wheel 86.

A print hammer I9I is pivotally mounted at I92 above the code discselector 13 between the type wheel shaft 84 andthe platen 81 and facingthe latter. The print hammer I9I has integral therewith a bail memberI93 which extends rightwardly from the print hammer IrSI, as viewed inFig. 3, and has integral therewith at the right-hand end thereof anoperating lever I94 (Figs. 1 and 3) pivotally mounted at I96 coaxiallywith respect to the pivotal mounting I92. The lever I94 carries aresilient impact receiving member I91 (F'ms, 1 and 3) which is disposedin the path of the outer end of striker member I34. The impact receivingmember I91 is adapted to be struck a sharp blow by the striker memberI34, when the latter is operated, to rotate the lever I94 clockwise, asshown in Fig. 1, and thus rotate the print hammer I9I clockwise, asviewed in Fig. 4, to reciprocate the type pallet then in alignment withthe print hammer I9I to effect printing by cooperation between theplaten 81 and the type face of one o the type pallets I52 or I93.

It will be observed that in Fig. 4, a' type pallet I63 of the upper rowof type pallets is aligned with the print hammer -I9I and the printingposition of the platen, due to the fact that the hub I12 which supportsthe type wheel 88 is in its lowermost position. At its lower end, thehub I82 is engaged by a horizontal arm I98 of a shifter frame I99located at the right side of the typing unit (Fig. 1) and arranged to belifted and lowered by the operation of shift bell cranks 20I and 202through connections fully described in the hereinbefore mentionedcopending application. When the shifter frame I99 is lifted by theoperation of the bell crank lever 29I, the type pallets I52 in the lowerrow are brought into alignment with the head of print hammer I9I and inalignment with the printing position of platen 81. Manifestly any typepallet in either row may be brought into operative alignment with theprint hammer by shifting the type wheel to the proper level and stoppingthe type wheel in a particular position as determined by the cooperationof the stop arm 83 with a particular selectable stop pin 19. When thetype wheel is shifted upwardly or downwardly on the shaft 84, the keywayrecesses I41 and I16 slide on type wheel driving arm I88.

It will be noted that there is shown in Fig. 6 a

type pallet differing from those shown in Figs.

and 7 in that the face thereof carries no character by which printingcan be effected and the shank thereof is shorter than the shanks I54 andI61. The blank or dummy pallets 283 shown in Figs. 3 and 6 are employedin those stop positions of the type wheel at which the printing of acharacter is not desired; for example, functions such as shift, unshift,"carriage return, line feed, etc., are functions which must be performedunder certain operating conditions and it is usually not desirable toprint characters when such functions are performed. It is fully setforth in the copending application that the code disc selector 13selects a stop pin 19 for functions as well as for characters and thatthe type wheel is brought to a stop at certain positions correspondingto the function selections. In order that printing may be avoided whenthe function is performed, the short shanked pallets 203 are provided,which the print hammer i9! will not reciprocate a sufficient distance tobring the pallet into cooperation with the platen 81 and which carriesno character to be recorded. With this arrangement it is not necessaryto disable the striker member I36, the lever I94, or the print hammerI99 when a function is performed.

Referring particularly to Fig. 1 for a description of the operation ofthe typing unit 4|, attention is directed first to the'selectormechanism 56, the selector magnet 59 of which receives signalingimpulses from a suitable telegraph circuit and with the cooperation ofcam barrel SI, which is released for rotation at the beginning of eachgroup of code impulses, sets the swordand-T selector mechanism 63 bymeans of the selector lever 82. The setting of T-levers B4 in accordancewith received code impulses is transmitted to the code discs 15, throughthe transfer levers 68, and a particular stop pin 19 corresponding tothe code signal received by the selector magnet 59 enters the path oftype wheel stop arm 83. Type wheel shaft 84 is permitted to rotate untilit is stopped by engagement of the stop arm 83 with the selected stoppin 19. In this manner a particular type pallet I52 or I63,-dependingupon the previously established shift or unshift condition ot the typewheel, is brought into operative alignment with the print hammer I9I.

At a predetermined point in the cycle of operation of the selector cambarrel 5|, the clutch throwout lever H3 is tripped by lever H8 and camsleeve H1 is set in rotation. The sleeve I I1 imparts rotation to thecams H9 and H8. As cam II9 rotates, its follower (not shown) is operatedto cause counterclockwise rocking of lever I3I to which is articulatedbar I32. Abutment I33 carried by bar I32 rotates striker member I34counterclockwise through its engagement with lever arm I31 thereof, andthus a sharp blow is imparted to impact receiving member I91. The blowis transmitted through lever I94, bail I93, and print hammer I9I to theparticular type pallet which is aligned with the hammer to cause it tobe propelled toward the printing platen 81 to effect printing on paperwhich may be carried by the platen. The character printing movement ofthe type pallets I52 or I63 is effected in opposition to their retaining"springs I51 or I68 which are operative. after printing of the characterhas been effected to restore the type pallets to their unoperatedpositions in abutment with the flanges I43 and M4.

In the event that the selected stop pin 19 corresponds to a function tobe performed instead of to a character to be printed, one of the dummytype pallets 203 may be aligned with the print hammer I9I in the stopposition of the type wheel 86, and since the dummy pallet 283 carries noprinting element, and since its; shank is shorter than those of thecharacter carrying type pallets, it will not be actuated to produce anymarking upon the paper carried by the printing platen.

It should be noted particularly that by means of the type wheelstructure described herein, including the individual type elements,great flexibility of arrangement is afforded. The character printingelements may be arranged in any desired order in either the upper or thelower position to permit the association of any desired characters withparticular code selections. Thus, printing units as shown in Fig. 1 maybe manufactured in accordance with a single standard and may be suitedto individual requirements by providing type wheels having the typepallets arranged in accordance with such individual requirements. Also atyping unit which has been individualized by being provided with a type'wheel having a particular arrangement of type pallets may be readilyconverted to conform to a different standard merely by rearranging thetype pallets within the type wheel structure or by substituting othertype pallets. I

It will be understood that the invention is not limited to the provisionof dummy type pallets as shown. in Fig. 6 in those positions whichcorrespond to function selections. tain circumstances, be desirable toeffect the printing of a character simultaneously with a performance ofa function in order that there may be permanent record of theperformance of that function and in such cases type pallets inaccordance with Figs. 5 or 7 and provided with any desired symbol may beemployed.

The springs I51 and I88 engage all of the type pallets in the particularset with which each is It may, under cerassociated, and thus yieldinglyretain all of the type pallets in the set under uniform tension. Thefloating ring Iii is provided as a safety feature to prevent escape ofthe type pallets from the annulus Ill and scattering of the pallets dueto centrifugal force should breakage of either of the springs I61 or I"occur.

Although a particular embodiment of the in-- vention has been describedherein, it will be understood thatthe apparatus is capable of manymodifications and substitutions in the various elements and combinationsthereof within the scope of the appended claims.

What is claimed is:

1. In a printing telegraph apparatus, a vertical shaft subjected to aconstant torque, the upper portion of said shaft being reduced indiameter to produce a supporting shoulder, a type wheel comprising a hubportion slidable on said upper portion and adapted under certainoperating conditions to rest on said shoulder, a disc portion secured tothe upper end of said hub, an annulus depending from said disc, saidannulus having a groove of constant depth and rectangular crosssectionin the periphery thereof whereby upper and lower integral flanges areprovided, type pallets slidable in radial slots in said annulus andarranged in two rows, printing means cooperating with the inner ends ofsaid type pallets, aligned keyways in the peripheries of said disc andsaid upper and lower flanges of said annulus, and an arm secured to theupper end of said shaft, said arm having at its outer extremity adepending portion adapted to be slidably articulated to said type wheelthrough the instrumentality of said keyways, so that said dependingportion is prevented from interfering with the operation of said typepallets by said printing means.

2. In a printing telegraph apparatus, a vertical shaft subjected to aconstant torque, the upper portion of said shaft being reduced indiameter to produce a supporting shoulder, a type wheel comprising a hubportion slidable on said upper portion and adapted under certainoperating conditions to rest on said shoulder, a disc portion secured tothe upper end of said hub, an annulus depending from said disc, saidannulus having a groove of constant depth and rectangular crosssectionin the periphery thereof whereby upper and lower integral flanges areprovided, type pallets slidable in radial slots in said annulus andarranged in two rows, printing means cooperating with the inner ends ofsaid type pallets, aligned keyways in the peripheries of said disc andsaid upper and lower flanges of said annulus, an arm secured to theupper end of said shaft, said arm having at its outer extremity adepending portion adapted to be slidably articulated to said type wheelthrough the instrumentality of said keyways, so that said dependingportion is prevented from interfering with the operation of said typepallets by said printing means, spaced flanges integral with said hubportion at the lower end thereof, and means embracing said hub portionbetween the spaced flanges thereof cooperable through the articulationbetween said type wheel and said depending portion for facilitating caseshifting movements of said type wheel, whereby interference between saiddepending portion, printing means and type pallets is prevented.

HOWARD L. KRU'M. CARL W. SWAN.

